The principle of CME has been adopted for many years with solid evidence and strong support by more and more surgeons as the optimal approach for colon cancer surgery [11–12]. It is reported that central nodal metastases occurs in up to 11% of cases (usually range from 0 to 5.8%)[13–14]. Therefore, CME with central vascular ligation (CVL) was thought to be potentially successful in removing lymph node metastases and avoiding vascular and neural invasion in the entire regional draining area. Therefore, it has become a standard form of colon cancer surgery[15].
A study investigating the extent of lymph node metastasis found that in 164 cases of right colon cancer with lymph node metastasis, majority of positive nodes were located less than 10 cm from the lesion, regardless of the position of the cancer[16], while less than one percent of positive lymph nodes were located further than 10 cm away from the cancer. Some studies also found that the longitudinal spread was only observed in the N1 zone (within 5 cm) and in the N2 (within 10 cm) pericolic station[17]. For left-sided colon cancers, longitudinal spread greater than 10 cm beyond the tumor was not found and the data for right-sided tumors is only 1–4%[18]. According to Japanese guidelines[19], longitudinal metastatic lymph nodes are rarely found greater than 10 cm beyond the tumor; therefore, resection of a 10-cm segment of normal bowel both, in the proximal and distal zones to the tumor is adequate. In contrast, for patients with metastases in epicolic and paracolic nodes greater than 10 cm from the tumor, a curative resection was not feasible. Toyota et al [7] found that for 24 patients (45.2%) with lymph node metastasis who were identified among the 53 patients with right-transverse colon cancer, there was no lymph node metastasis at the root of the ileocolic artery. Therefore, it can be inferred that the segment of the normal bowel proximal to the tumor is much longer in conventional laparoscopic extended right hemicolectomy for right-transverse colon cancer. However, laparoscopic segmental colectomy for right-transverse colon cancer may be a difficult technique, because the extracorporeal anastomosis (EA) needs long free intestines.
With improvements in surgical devices and technology, complete laparoscopic treatment for colon cancer with intracorporeal anastomosis (IA) has become widespread because of its advantages of being less invasive, having an earlier postoperative recovery time and a lower complication rate when compared to laparoscopic-assisted surgery with EA[20–21]. On the one hand, a recent meta-analysis including 3755 patients found that in IA, time to first flatus, time to defecation, time to liquid diet, hospital length of stay, postoperative infections and overall complications were estimated to be lower[22]. On the other hand, Kang Hong Lee et.al[23]found that the number of retrieved lymph nodes, the overall survival and the disease-free survival at three years were not significantly different between IA and EA. The resection and anastomosis need not be performed extracorporeally for IA and therefore a smaller portion of the intestine is required to be freed laparoscopically.
Based on the progress reported in theory and the techniques involved, we decided to perform complete laparoscopic extended hemicolectomy with preserving the ileocecal junction to treat right-transverse colon cancer and explore its safety and feasibility. The technical difficulty and longer operation times may be challenging because of the new techniques involved and higher BMI in the ileocecal junction-preserved group. However, the mean operation time for the ileocecal junction-preserved group was significantly shorter than the control group because the resection of the ileocecal junction and its related vessels were not needed. Therefore, we think the procedure with preserving the ileocecal junction is less time-consuming, especially for experienced surgeons. We also found no difference between the amount of blood lost, which is one of most important evaluation parameters. In terms of postoperative recovery, a significantly shorter time of first flatus and an earlier recovery of defecating frequency were found in the ileocecal junction-preserved group. The main cause of the significantly different improvements in these parameters in postoperative recovery can be attributed to the preservation of the ileocecal valve. Previous studies found a higher hydro-electrolytic loss and a greater difficulty in adapting to the postoperative diet when the ileocecal valve was resected[24]. The alterations in microbiota caused by an increased resection of the intestine may also correlate with this finding.
Moreover, in the ileocecal junction-preserved group in our study, the pathological outcomes are identical when compared with the control group. Although the mean lymph nodes yielded were fewer in the ileocecal junction-preserved group because of a lesser resection area of the intestine and mesentery, there was no difference between two groups. The mean achieved number was much greater than 12 nodes in the final surgical specimen count in both groups, meeting the demands of the TNM cancer staging system set by UICC (International Union Against Cancer) and American Joint Committee on Cancer [25]. There was no difference between two groups in the number of metastatic lymph nodes and rate of metastatic lymph nodes. Pathological diagnosis found negative resection margin in all the patients. Although the proximal resection margin was shorter in the ileocecal junction-preserved group, proximal and distal resection margins were more than 10 cm in the control group.
The limitations to our study were that it was a retrospective study and the present outcomes were from a single surgeon that represents a relatively small number of patients. However, the surgical procedures evaluated in this study were performed by an experienced surgeon with homogenous types of surgery and disease status of the patients. Prospective randomized controlled trials from multiple centers with larger sample sizes are now needed to confirm our results.